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AN bolt question

rv12iS-builder

Well Known Member
Friend
Is there a limit to the number of times an AN bolt (especially an AN-3) can be re-torqued and reused? Is there a way to tell if an AN bolt (that hasn't snapped into two pieces) has ever been over-torqued?

Thanks,
 
In a critical application, just use a new bolt every time. Heck, they only cost 15c so is it worth it to have to worry about it? Not for me.
 
as a friend keeps repeating

..."remember the Galloping Ghost". Replacement hardware is a lot cheaper than a critical failure.

More technically, torquing a bolt/ screw/ fastener stretches it. That's why engine bearing cap screws/ studs/ carry- throughs are replaced, for example. BUT, in most applications, you'll never see the stretch, and unless over-torqued, the tensile strength is so minimally degraded as to be a non-issue. [Once over- tightened, you have invaded the 'safety value' of both tensile and shear strength--please throw it out]

That being said, if you walk into a shop and there is not a set of bins with LOTS of new hardware -- turn around, walk away to live another day.
 
worried about over torque

Just to add, to ensure you are torquing at the correct amount your torque wrench needs to be checked / calibrated. Certificated shops do it annually, FAA inspectors like to check the paperwork.

If its a SnapOn torque wrench the truck usually has a method to check the wrench. That doesn't get you calibration paperwork, but it does let you know if the wrench needs adjustment.

A lot of folks will say if the wrench is set to zero after use, and never dropped, it should not be out of calibration. But it doesn't hurt to check it.
 
Is there a limit to the number of times an AN bolt (especially an AN-3) can be re-torqued and reused? Is there a way to tell if an AN bolt (that hasn't snapped into two pieces) has ever been over-torqued?

Thanks,

When in doubt,,,,throw it out. Get together a good selection of AN hardware and keep it organized. You can then just pitch questionable bolts and nuts and having the replacements on hand makes that decision so much easier. Every so often I will go through my organizers making a list of any hardware I am running shy of and place an order to restock.
 
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